Identifying Anatomical Structures

ABSTRACT

Aspects described herein disclose devices, systems, and methods for use in contexts such as minimally invasive surgery (MIS). A device is provided herein having a proximal portion and a distal portion, and an ultrasound transducer may be disposed within the distal portion and configured to scan tissue and identify certain portions of a patent&#39;s anatomy during the scanning process. The results of the detection may be presented to an operator of the device aurally and/or visually, such as in a 3-D volumetric image. By scanning the tissue, identifying the anatomy, and presenting the results to an operator, unnecessary damage to elements of the patients anatomy may be avoided or lessened. In some aspects, multiple transducers may be positioned on the device to increase the scanning range and/or scanning accuracy of the device. The device may provide an inner channel for the passage of surgical tools while scanning tissue.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/063,152, filed on Mar. 7, 2016 entitled IDENTIFYING ANATOMICALSTRUCTURES, which claims priority to U.S. Provisional Patent ApplicationSer. No. 62/129,866, filed Mar. 8, 2015 and entitled Device and Methodfor Identifying Anatomical Structures and to U.S. Provisional PatentApplication Ser. No. 62/129,862, filed Mar. 8, 2015 and entitled NerveMapping System. U.S. application Ser. No. 15/063,152 is acontinuation-in-part of International Application PCT/US15/50404, withan international filing date of Sep. 16, 2015 entitled IDENTIFYINGANATOMICAL STRUCTURES, which claims priority to U.S. Provisional PatentApplication Ser. No. 62/051,670, filed Sep. 17, 2014 and entitled“DEVICE AND METHOD FOR IDENTIFYING ANATOMICAL STRUCTURES”. The contentsof the applications listed above are hereby incorporated by reference intheir entirety for all purposes. This application also incorporates byreference in their entireties for all purposes the following relatedapplications: U.S. Provisional Application Ser. No. 61/847,517, filedJul. 17, 2013, entitled Direct Visualization Dissector and RetractorSystem for Minimally Invasive Procedures, U.S. Provisional ApplicationSer. No. 61/867,534, filed Aug. 19, 2013, entitled UltrasonicVisualization, Dissection, and Retraction System for Minimally InvasiveProcedures, U.S. Provisional Application Ser. No. 61/868,508, filed Aug.21, 2013, entitled OCT Visualization, Dissection, and Retraction Systemfor Minimally Invasive Procedures, U.S. Provisional Application Ser. No.61/899,179, filed Nov. 2, 2013, entitled Nerve Detection System, U.S.Provisional Application Ser. No. 61/921,491, filed Dec. 29, 2013,entitled System and Method for Identifying Anatomical StructuresUltrasonically, U.S. Provisional Application Ser. No. 61/929,083, filedJan. 19, 2014, entitled System and Method for Identifying AnatomicalStructures Ultrasonically, U.S. Provisional Application Ser. No.61/977,594, filed Apr. 9, 2014, entitled System and Method forIdentifying Anatomical Structures Ultrasonically Employing Two or MoreTransducers, and U.S. Non-Provisional application Ser. No. 14/329,940,filed Jul. 12, 2014, entitled Device and Method for IdentifyingAnatomical Structures.

BACKGROUND

Surgical techniques utilizing minimally invasive surgery (“MIS”) arebeing rapidly adapted to replace current traditional “open” surgicalprocedures. “Open” procedures typically require larger skin incisionsthat may cause significant collateral damage to uninvolved anatomicstructures. For example, intervening soft tissue (e.g., tendons,ligaments, facet capsules, muscles, and so on) may be cut and evenpotentially excised to allow for direct surgical visualization of theoperated-upon area or anatomical structure.

In contrast, minimally invasive techniques, which may also be referredto as “percutaneous” techniques, involve significantly smaller incisionsand are less traumatic to the patient's anatomy. Soft tissues may bepreserved with minimal collateral damage to the uninvolved anatomy.Typical benefits of MIS may include decreased blood loss, decreasedpostoperative pain, smaller scar formation, decreased cost, and a fasterrehabilitation for the patient than in “open” or conventional surgicaltechniques.

Minimally invasive surgery techniques are currently being adapted to avariety of surgical procedures. For example, minimally invasivetechniques in the form of laparoscopic procedures, such as alaparoscopic colectomy for carcinoma of the colon, have been developed.More recently, surgeons have utilized MIS in spinal surgeryapplications.

BRIEF SUMMARY

Present MIS techniques are unable to accurately and consistently detectand avoid key anatomical features, such as neural elements, potentiallyresulting in profound neurological sequelae and deleterious impacts toother systems. For example, even a minimally invasive surgicalinstrument, if impacting or contacting with nervous system elements(e.g., nerves, spinal cord) may result in loss of sensation, sensoryoverload, pain, or other unwanted or harmful effects. Detection andidentification of anatomical features may assist in combating theseproblems and other problems that may become apparent upon reading ofthis disclosure.

Accordingly, in one aspect of the present disclosure, a device may beprovided for minimally invasive surgery and may include a bodycomprising a proximal portion, a distal portion, and a main portionformed between the proximal portion and distal portion. At least oneultrasound transducer may be arranged at the distal portion of the bodyand may be configured to scan a region extending away from the mainportion of the body. The device may include a signal processing unithaving at least one processor and memory storing instructions that causethe at least one processor to receive a signal from the at least oneultrasound transducer and identify an anatomical structure based on thesignal.

In some embodiments, the device may include a hollow channel and anannular shaped tip to allow the passage of surgical tools in the channelfor performing procedures while collecting data for use in mappinganatomical tissues. In these embodiments, ultrasonic transducers may bearranged on the distal end of the device, on the annular shaped tip.

In another aspect, a device may be provided for minimally invasivesurgery. The device may include a proximal portion, a distal portion, amain body formed between the proximal and distal portions of the devicehaving a longitudinal axis and at least one ultrasound transducerdisposed within the distal portion of the device and configured to scana region adjacent to a distal end of the distal portion of the device.

In another aspect, a method may be provided and may include receivingdata from at least one ultrasound transducer arranged at a distalportion of a body and configured to scan a region extending away from amain portion of the body. The method may also include processing thedata to identify an anatomical structure located within the region, andoutputting an indication associated with the anatomical structure.

In another aspect, a method for identifying a target anatomy may beprovided with a device having a distal portion and at least oneultrasound transducer at least partially disposed within a main body ofthe device. The method may include scanning an anatomy of a patientanatomy for the target anatomy, determining a voltage trace of thepatient's anatomy, comparing the voltage trace of the patient's anatomyto a predetermined voltage trace of the target anatomy, and sending anotification if the voltage trace of the patient's anatomy matches thepredetermined voltage trace of the target anatomy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of one embodiment of a device.

FIG. 2 is a side view of another embodiment of the device of FIG. 1.

FIG. 3 is a functional diagram of the ultrasound imaging system that maybe used in one embodiment of the present disclosure.

FIG. 4 is a diagram of an ultrasound transducer that may be used in oneembodiment of the present disclosure.

FIG. 5 is another functional diagram of one embodiment of the ultrasoundimaging system that may be used in an embodiment of the presentdisclosure.

FIG. 6 is one embodiment of the device having more than one ultrasoundtransducer disposed therein.

FIG. 7 is another embodiment of the device having one ultrasoundtransducer disposed therein.

FIG. 8 depicts the scanning width of a transducer.

FIG. 9 depicts the scanning width of a transducer in one configuration.

FIG. 10 is another embodiment of the present disclosure where one of thetransducers is positioned at an angle with respect to the othertransducer.

FIG. 11 depicts the scanning width of the embodiment of FIG. 10.

FIG. 12 is yet another embodiment of the present disclosure where twotransducers are angled towards the longitudinal axis of the device.

FIG. 13 depicts scan images of a target anatomy taken by one embodimentof the present disclosure.

FIG. 14 is a scan and A-line image scan of the target anatomy capturedby one embodiment of the present disclosure.

FIG. 15 depicts the configuration of one embodiment of the presentdisclosure.

FIG. 16 depicts images of the target anatomy captured by one embodimentof the present disclosure.

FIG. 17 depicts additional images of the target anatomy captured by oneembodiment of the present disclosure.

FIG. 18 is a scan of the target anatomy captured by one embodiment ofthe present disclosure.

FIG. 19 depicts one embodiment of a retractor system that can be usedwith embodiments of the present disclosure.

FIG. 20 depicts one embodiment of the dilator system that can be usedwith embodiments of the present disclosure.

FIG. 21 is one embodiment of the present disclosure that is incorporatedinto a glove.

FIG. 22 is a partial side view of the embodiment disclosed in FIG. 21.

FIG. 23 is a front cross-sectional view of one embodiment of the gloveembodiment disclosed in FIG. 21.

FIG. 24 is a front cross-sectional view of another embodiment of theglove embodiment disclosed in FIG. 21.

FIG. 25 is a front cross-sectional view of yet another embodiment of theglove embodiment disclosed in FIG. 21.

FIG. 26 is diagram of another embodiment of the present disclosure thatutilizes Optical Coherence Tomography.

FIG. 27 is one embodiment the probe used with the embodiment disclosedin FIG. 26.

FIG. 28 depicts two embodiments of the probe used with the embodimentdisclosed in FIG. 26.

FIG. 29 is a side view of one embodiment of the present disclosurehaving direct visualization capability.

FIG. 30 is a cross-sectional view of the embodiment disclosed in FIG.29.

FIG. 31 is another embodiment of the present disclosure having directvisualization capability.

FIG. 32 is a partial cross-sectional view of the embodiment disclosed inFIG. 31.

FIG. 33 is a partial front cross-sectional view of the embodimentdisclosed in 29.

FIG. 34 is another embodiment of the present disclosure disclosed inFIG. 29.

FIG. 35 is a side cross sectional view of another embodiment of thepresent disclosure disclosed in FIG. 31.

FIG. 36 is yet another embodiment of the conduit disclosed in FIG. 29.

FIG. 37 is yet another embodiment of the conduit disclosed in FIG. 29.

FIG. 38 depicts one embodiment of the present disclosure in use with aretractor system.

FIG. 39 depicts one embodiment of the retractor system of the presetinvention.

FIG. 40 depicts another embodiment of the retractor system of the presetinvention.

FIG. 41 depicts an illustrative graph of Scan line energy as a nervediscriminant.

FIG. 42 depicts an illustrative user interface design window containinga designed bandpass filter and specifications.

FIG. 43 depicts an illustrative application of a bandpass filter on thereceived RF signals, thereby suppressing low frequency noise near thetransducer surface.

FIG. 44 depicts examples of SVM classification schemes for separable andnon-separable data.

FIGS. 45A & B depict a plot matrix showing two-dimensional (2D)relationships between the feature variables.

FIG. 46 depicts an illustrative receiver operating characteristic (ROC)curve defining performance of the trained SVM.

FIG. 47 illustrates a computing device in accordance with one or moreaspects described herein.

FIG. 48 shows the device viewed from the distal end as in an embodimentof the present disclosure.

FIG. 49 shows the device viewed from the side as in an embodiment of thepresent disclosure.

FIG. 50 shows the distal face of the device as in an embodiment of thepresent disclosure.

FIG. 51 depicts placement of the device on the surface of the psoasmuscle as in an embodiment of the present disclosure.

FIG. 52 is another depiction of the placement of the device on thesurface of the psoas muscle as in an embodiment of the presentdisclosure.

FIG. 53 depicts a probe inserted into the device on the surface of thepsoas muscle as in an embodiment of the present disclosure.

FIG. 54 depicts a nerve map in a viewing window in accordance withaspects of the present disclosure.

FIG. 55 depicts a visual representation of Kambin's triangle.

FIG. 56 depicts the device in a position targeting Kambin's triangle, asdescribed herein.

FIG. 57 depicts a surgical incision targeting access to a location onthe spine.

FIG. 58 depicts a surgical approach targeting a portion of the spine.

DETAILED DESCRIPTION

To help understand the present disclosure, the following definitions areprovided with reference to terms used in this application.

Throughout this specification and in the appended claims, whendiscussing the application of aspects of the present disclosure withrespect to the body's tissue, spine or other neural elements, the term“proximal” with respect to such a device is intended to refer to alocation that is, or a portion of the device that is, closer to theoperator. The term “distal” is intended to refer to a location that is,or a portion of the device, further away from the operator.

The embodiments below are described with reference to the drawings inwhich like elements are referred to by like numerals. The relationshipand functioning of the various elements are better understood by thefollowing detailed description. The embodiments as described below areby way of example only and the present disclosure is not limited to theembodiments illustrated in the drawings.

According to one or more aspects of the present disclosure, a devicecapable of detecting target anatomical structures may be provided. Thedevice may utilize ultrasound and/or Optical Coherence Tomography (OCT)technology as the device is being advanced through a patient's anatomy.The device may have a distal portion having a tip, where the tip can beused to dissect a patient's anatomy without puncturing or tearing thepatient's anatomy and while simultaneously allowing the device toinspect the anatomy as it is being dissected by the tip. While thedevice discussed herein is discussed in the context of a device that canbe held by an operator, it is contemplated that the device and/or partsof the device may be used during automated procedures such as thosebeing performed by robotic and other similar systems.

In one embodiment, shown in FIG. 1, the device 10 has a proximal portion12 and a distal portion 14 with a main body 16 disposed between theproximal and distal portions 12, 14. The main body 16 has a proximal end18 and a distal end 20 and is defined by a longitudinal axis L. Theproximal end 18 may have a handle (not shown) or gripping portion (notshown) attached thereto. The length of the main body 16 may vary, butcan include a length of 50 to 300 mm; however, in some embodiments thelength may fall outside of this range. Similarly, the outer diameter ofthe main body 16 may vary and can include an outer diameter of between 3mm and 20 mm. The main body 16 can be made out of any preferablesurgical grade material, including but not limited to, a medical gradepolymer including PEEK (polyether ether ketone), stainless steel, carbonfiber, and titanium. The main body 16, and one or more of the componentsof the device 10 generally, may contain radio-opaque markers to allow anoperator to detect the location of the device 10 with respect to theanatomy of a patient via radiographic imaging.

As shown in FIG. 1, the distal portion 14 of the device 10 includes atip 22. The tip 22 may be hemispherical in shape, as illustrated in FIG.1, but it is contemplated that the tip 22 may also be of a differentshape. For example, and without limitation, the tip 22 may have asemi-spherical, conical, pyramidal, spear or aspherical shape. The tip22 may be configured to dissect a patient's anatomy, such as a muscle,without tearing or disrupting the patient's anatomy as it passes throughthe tissue. As a result, the outer diameter of the tip 22 may have adiameter ranging anywhere between 1 mm and 50 mm and preferably between2 mm and 9 mm. It is appreciated that the outer diameter of the tip 22may fall outside of this range as well. It is further appreciated thatthe tip 22 is optional such that particular embodiments of the device 10may not include the tip 22.

As illustrated in the embodiment shown in FIG. 1, the main body 16 ofthe device 10 may be substantially straight. However, it is contemplatedthat the main body 16 may have different shapes, including having acurved shape with a non-zero radius of curvature. An example of such anembodiment is illustrated in FIG. 2, which may be used for MIS requiringaccess through the presacral space of a patient. The main body 16 mayalso take on an “L”, “C”, “U” shape or a shape there between.

The device 10 may include ultrasonic capability. A purpose of thisdevice may be to serve as an instrument that features a specificallypatterned array of high frequency ultrasound transducers and amonitoring system that collects spectral properties of specific tissuein the body. For example, the system may be able to detect the spectralproperties of muscle, fat, nerve and bone. As the anatomy is stimulatedby the ultrasound transducer(s), it will emit a specific spectralproperty that can be detected by the monitoring system. The system mayexamine scan line images and seek specific parameters of amplitude,shape, and other spectral content in order to differentiate the signalscoming from the nerve and signals coming from surrounding tissues. Forexample, nerve tissue may be hypoechoic as compared with the surroundingtissue. However, there are internal structures that provide features inthe signal that identify the nerve from single scan lines or RFproperties. The system will inform the operator that the device isadjacent to or proximate to the specific type of anatomy that isdetected by the system. The device can allow a surgeon to identify andavoid certain portions of a patient's anatomy (e.g. nerve) whenperforming a minimally invasive procedure.

The device 10 may be equipped with ultrasound imager 24 to detect apatient's anatomy as shown in FIGS. 3-5. The ultrasound imager 24 mayinclude a transducer 26 that is configured to emit sound waves and maybe disposed at the distal end 20 of the device 10. As shown in FIG. 4,the transducer 26 may include a single element focused transducer, andmay have a frequency operation range that includes an operating range ofapproximately 10-40 MHz. In some aspects, the operating range may behigher or lower than this range of frequencies. Additionally oralternatively, transducer 26 may include a micro machined array, such asa capacitive micromachined ultrasonic transducer (CMUT), having multiplechannels. The desirable frequency may vary depending on the applicationand target anatomy. For example, in one embodiment a frequency or rangeof frequencies may be selected for detecting nerve from surroundingtissues and adjacent anatomy on b-mode (2D) ultrasound images based onimage texture and echogenicity. Reliably distinguishing between nerveand muscle tissue in real time may require quantitative approaches, andmay require automated or manual calibration of the system to estimatetissue-specific properties. In some aspects, a meta-analysis comparingultrasound to nerve-stimulation may result in superior outcomes forultrasound guidance.

As shown in FIGS. 3 and 5, the transducer 26 may be in communicationwith a RF-pulser/receiver 28, which may be in communication with ananalog to digital converter 30, which may be in communication with adigital signal processor 32 and an output 34 such as a monitor.

In one embodiment, the transducer 26 converts an electric signal orpulse generated from the RF-pulser/receiver 28 into a sound wave andthen converts a reflected sound wave back into an electrical signal. Theultrasound transducer 26 launches sound pulses, which may be short,high-frequency non-damaging sound pulses, into the tissue, and then maywait to hear the reflection from the tissue. Since the speed of sound intissues is high (˜1500 m/s), this process may take a few milliseconds toimage a few millimeters of tissue. As referenced above, theRF-pulser/receiver 28 may generate an electrical impulse that may besent (e.g., via a cable) to the transducer 26 to generate a sound wave,and may also receive a signal from the transducer 26 generated by thereflected sound waves that the transducer 26 receives. The analog todigital converter 30 converts the analog radiofrequency signal receivedfrom the transducer 26 into a digital form that a computer may analyze.The digital signal processor 32 processes the digitized signal receivedfrom the digital converter 30. Signal filtering and processingoperations may be programmed into the hardware, firmware, and/orsoftware of various components of the system (e.g., the digital signalprocessor 32) to detect the reflected signal properties of the tissueand distinguish between nerve and muscle tissues in real-time. Once anerve tissue signature is detected, a hardware, firmware, and/orsoftware system may communicate with the output 34. The output 34 mayinclude a visual monitor that may be programmed to display the anatomyor signals indicative of the anatomy (e.g., via actual images orprogrammable color configurations (red/yellow/green)) and/or asound-generating device which may be controlled to emit an audibleindicator (e.g. alarm or a “beep”). For example, the sound-generatingdevice, such as a speaker, may emit a “beep” when the device 10encounters/detects the presence of target anatomy (e.g. nerve) within apredetermined range (e.g. 1 mm to 10 cm).

It is appreciated that one or more of these components may be inwireless communication with one another, may be combined into one orcomponents, and other additional components may be in communicationbetween each of these components or one or more identified componentsand may not be included in a particular embodiment.

In one embodiment, the outer diameter of the transducer 26 may beapproximately 3 mm, but may range anywhere between approximately 1 mmand 10 mm. Further, the transducer 26 is configured to be disposed in avariety of locations with respect to the device 10. For example, asshown in FIG. 6, the transducer 26 may be disposed at the distal end 20of the main body 16 or at the tip 22 portion of the distal end 20. Thetransducer 26 may also be removable such that it can be removablydisposed within a conduit 36 formed within the device 10 and removedonce a working space is identified and accessible. In some aspects, theworking space may be the space created by insertion and/or manipulationof the device 10 within the patient's anatomy.

Multiple transducers 26 may be provided as part of the device 10. Insome aspects, two or more transducers 26 may be side positioned (e.g. oneither side of the main body 16) so as to provide for multi-directionalscanning of the patient's anatomy to detect a nerve. The side positionedtransducers may be configured to scan the anatomy around in acircumferential direction around the main body 16, and may detect thenerve (or other target anatomy) that was not detected by a transducerpositioned at the distal end 20 of the main body 16. Themulti-directional scanning enables the system to generate a scan imageof the patient's anatomy in multiple directions as the device 10 isadvanced through the patient's anatomy.

Returning to FIG. 6, the device 10 may include at least one ultrasoundtransducer 26 (such as a high frequency ultrasound transducer) that isused to stimulate a patient's anatomy, such as muscle, fat, nerve, andbone, and so on. A series of transducers 26 (e.g., a transducer, two ormore transducers) may be disposed along the length of the device 10 toallow for a wider pattern of ultrasonic stimulation of the surroundinganatomy. In this embodiment, there may one transducer 26 on the distalend of the device 10 that emits an ultrasonic frequency in a directionthat is substantially parallel to the longitudinal axis of the device10. There may be another transducer 27, adjacent to the first transducer26, that emits ultrasonic frequency along a path that is substantiallyperpendicular to the longitudinal axis of the device 10. It can beappreciated that the transducers 26 and 27 can be orientated in anydirection that is required for the particular application.

FIG. 7 depicts one embodiment where a 5 MHz transducer 26 is located onthe distal end 21 of the device. In such an embodiment, the diameter ofthe transducer 26 may be 3 mm and the transducer may be forward facing.In such an embodiment, the scanning range is approximately 14 mm. Insome aspects, an area of the scanning region (hatched section in FIG. 8)by a transducer 26 may not exceed the outer diameter of the transducer.This may be because the scanning width is circumscribed by the outerdiameter of the transducer 26 and the peripheral limitations of thetransducer 26 such that the transducer 26 cannot identify or scan aregion that lies beyond of the diameter of transducer 26.

Accordingly, in some aspects such as those disclosed herein where thetransducer 26 is housed within a device 10, the transducer 26 may beunable to scan the region that is directly front of (distal to) theouter portions of the device that houses the transducer 26. This region44 is depicted in FIG. 9. One result of this is that the target anatomymay go undetected if it is positioned beyond the scanning region of thetransducer 26.

In some aspects, for example to detect target anatomy that lies justbeyond the scanning region of the transducer 26 (i.e. outside of thescanning diameter), the device 10 may include two or more transducerspositioned at an angle relative to one another. For example, as shown inFIGS. 10 and 11, the first transducer 40 may be positioned at an anglewith respect to the outer edge of the main body 16. The angle may bemeasured from the face of distal end 21 of the device 10, or may bemeasured from the horizontal axis that intersects the longitudinal axisof the device 10. The angle α in this embodiment is 7° but it isappreciated that it can vary from 0° to 180° depending on the particularembodiment. Further, in this embodiment, the angle may be formed betweenthe edge of the transducer 26 and the adjacent outer edge of the mainbody 16.

Transducer 40 may be angled with respect to any portion of the main body16. For example, the first transducer 40 may be angled by pivoting thefirst transducer 40 about the portion positioned along, or closest to,the longitudinal axis of the main body 16 as shown in FIG. 12.Specifically, as shown in FIG. 12, the transducers 40, 42 may be angledtowards the longitudinal axis of the main body 16 such that the angle oftilt, al aa, are measured as the angle of the transducer from thelongitudinal axis of the main body 20.

In the embodiment shown in FIG. 10, the first transducer 40 may bepositioned at an angle (e.g., 7° from the edge of the main body 16)allowing the first transducer 40 to scan a region extending beyond theouter edge of the main body 16. Angling the first transducer 40 mayallow the device 10 to scan and detect any target anatomy residingoutside of the scanning region of a transducer that is not angled withrespect to the main body 16 of the device. A region that may be scannedby the first angled transducer 40 in this particular embodiment is shownin FIG. 10.

The two transducer elements may fit on the tip of a device 10. This mayallow, for example, the device 10 to detect backscattered signals. Insome aspects, the device 10, and/or the two transducer elements may beconfigured to detect the presence of nerves or other neural elementsexisting distally up to 1 cm from the probe tip 22 (e.g., the nerves orneural elements may be in the pathway of the device). In some aspects, adevice may be provided with transducers having different stimulatingfrequencies (e.g., a first transducer 40 may stimulate with a frequencyof 5 MHz, and a second transducer may stimulate with a frequency of 10MHz). Beam patterns or fields emitting from the sources may be modeledusing an ultrasound simulation program assuming an element diameter of 3mm and a focal number of 3 (f/3).

In some aspects, two transducer elements 40, 42 may be positioned at thetip of the probe. The tilted element 40 faces outward with an angle oftilt, such as 7°. The tilted element may have one end at the edge of theprobe. The un-tilted element 42 may be centered from the edge of thedistal portion of the device 10. This configuration may allow the device10 to be rotated as it is snaked through the tissue so that the crosssectional surface area of the probe may be at least 1 cm above the probesurface.

The diameter of the transducers 40, 42 may vary and can range from 1 mmto 20 mm. For example, in the embodiment shown in FIG. 10, the firsttransducer and second transducers 40, 42 each have a diameter ofapproximately 3 mm. It is not necessary for the transducers to have thesame diameter of one another and they may be staggered as shown in thetop view of FIG. 10.

The main body 16 can be rotated so as to allow the first transducer 40to scan the entire outer region to detect whether any target anatomy ispresent that is just beyond the scanning area of a forward facingtransducer. By rotating the main body 16 about its longitudinal axis,the first transducer 40 can scan the outer region that does not fallwithin the scanning region of a transducer that is not angled withrespect to the main body 16 of the device.

The number of angled transducers may vary and they may be positioned atvarious angles with respect to the distal end of the main body 16. Forexample, as shown in FIG. 12, the first and second transducers 40, 42are positioned toward one another so that their scanning areas cross toprovide a scan of the area distal to the distal portion 20 of the device10 and a region beyond the area directly in front of to the outerdiameter of the transducers 40, 42 as shown in FIG. 9. Also, thetransducers 40, 42 may be positioned at an angle on more than one axiswith respect to the distal end of the main body 16.

The device 10 can be configured to determine the b-mode scans of thepatient's anatomy and associated data, including, for example, thevoltage trace from a scan line in the b-mode image. The voltage tracefor certain anatomical parts (e.g., a nerve) may have a unique voltagetrace that may be used to detect like anatomical parts within thepatient's anatomy. One way to detect like anatomical parts may be bycomparing the voltage trace from a scan line of a b-mode image to theknown voltage trace from the scan line of the target anatomy.Specifically, the b-mode scans (and associated data, such as a-scanlines, voltage traces, and the like) may be captured by the device 10.The scans and/or data may be compared to the pre-determined b-mode scans(and associated data) of known anatomical features (e.g., nerve) todetermine whether the region captured by the b-mode scan from the device10 contain the target anatomy.

The device 10 may be used in conjunction with a neuromonitoring systemcapable of detecting certain portions of a patient's anatomy, includingneural elements that include a nerve, nerve bundle, or nerve root. Forthe purposes of this discussion, the device 10 and neuromonitoringsystem will be discussed with respect to detecting a patient's spinalnerve but it is contemplated that the device 10 and neuromonitoringsystem can be used to detect other nerves (peripheral and central) aswell as the spinal cord. One type of neuromonitoring system that can beused in conjunction with the device 10 is disclosed in U.S. Pat. No.7,920,922, the entirety of which is incorporated by reference herein.

Experimentation

The discussion below is directed to the experiment used to determine thetarget ultrasonic frequency that can be used to detect nerve using thedevice 10 and whether the b-mode scan images captured by the device 10,which is inserted into the patient's anatomy, is comparable to resultscaptured by traditional non-invasive ultrasound devices. Both targetobjectives were accomplished using the following process.

FIG. 13 illustrates exemplary data indicative of a scan of a sciaticnerve of a rabbit with a clinical ultrasound array system. The scan wasperformed before and after euthanizing the rabbit to be sure that thenerve could be seen in both cases. FIG. 13 depicts b-mode images (nervecross-sectional view) for alive (left, image 1300) and dead (right,image 1350). The nerve may be seen in each case (area pointed to bywhite arrow on image 1300 and image 1350).

The nerve was scanned using a high frequency (40 MHz) probe with thebottom of the nerve still attached to the muscle and the nerve centeredin the probe's depth of field. FIG. 14 illustrates a b-mode image 1400of this scan. The image 1400 shows (from top to bottom): water, nerve,and muscle. The nerve separates from the muscle towards the right sideof the image, and you can see a gap between the nerve and the muscle.FIG. 14 also illustrates a plot 1450 depicting the voltage trace from ascan line in the center of the b-mode image, indicated by the verticalline.

The hind limb sciatic nerve was scanned with a 20 MHz single-elementprobe though the leg muscle. The muscle was kept intact, and the skinremoved to provide a window to see into the muscle. The image 1500 shownin FIG. 15 illustrates the setup.

A clinical scan was performed before scanning with the 20 MHz probe.Images 1600 and 1650 from the clinical scan of the nerve are shown inFIG. 16, and images 1710 and 1720 from the scan performed by the 20 MHzprobe are shown in FIG. 17. A comparison between the clinical imagingsystem and the 20 MHz probe system suggests that both techniques producesimilar images. For example, the cross-section and length-wise (withrespect to the long direction of the nerve) scan planes both show thenerve in the background muscle for both the clinical system and the 20MHz system.

The 20 MHz results are important for at least two reasons: First, theresults show that the contrast inside the muscle exists at 20 MHz asdemonstrated in the left image 1710 in FIG. 17. Second, the depth ofpenetration for the 20 MHz signal was sufficient to be seen at more than1 cm of depth. This may be the distance away from the surgical proberequired for detecting the nerve. Therefore, this suggests that if thesignals can be used to detect the nerve, the signal strength andpenetration should not be an issue at the chosen ultrasound frequencies.

FIG. 18 depicts an image 1800 of a single scan line through the nerve.There are characteristic signatures from the nerves that can be used todetect the nerve from a single scan line.

In another experiment, a dual element transducer 40, 42, having aconfiguration similar to the embodiment disclosed in FIG. 10 wasutilized. This embodiment was used for testing of sciatic nerves of 22rabbit legs post-mortem. A total of 142 sets of radio frequency (RF)data were collected. Each slice of data was recorded over a 30 mmlateral distance capturing an axial region of approximately 5-20 mm fromthe transducer surface. Imaging performance was evaluated whenconducting a sector scan of −35° to 35° at a depth of up to 1.5 cm and acenter frequency of up to 15 MHz. The ultrasonic transducer used forscanning was dual-element, 10 MHz transducer, where each element was 3mm in diameter with an f-number of 3. Images were acquired using aPulser/Receiver, the settings of which are shown in the table below.

TABLE 1 Pulser/Receiver settings Pulse Repetition Frequency 200 MHzEnergy 12.5 uJ Damping 25 Ohms High Pass Filter 1 MHz Low Pass Filter 20MHz Input Attenuation 0 dB Output Attenuation 0 dB Gain 20 dB

As discussed above, the device was used to capture an ultrasonic B-modeimage, where the sciatic nerve may be identified as an isolated,hyperechoic region, usually elliptical or circular in nature as seenbelow. As such, one of the first attempts to classify the images wasbased on the thresholding on the energy of the received scan line. Fromthe data displayed in FIG. 41, for example, it may be seen that the scanline energy does allow for the detection of the presence of the sciaticnerve. Using energy alone, however, as a classification criterion maynot be adequate to distinguish between the diffuse, weak signature ofthe nerve with the sharp, strong signature of an isolated strongscatterer (e.g., data point 4100 in FIG. 41).

Low frequency ringing may also be present in the received RF scan lines,particularly near the surface of the transducer. Spectral analysis ofthe ringing may indicate a high noise component, such as a noisecomponent between 500 kHz and 2 MHz. To combat this noise, the receivedRF may be passed through a finite impulse response (FIR) bandpassfilter, such as software, hardware, and/or firmware configured using thedesign specifications described in Table 2 and illustrated in exampleuser interface 4200 of FIG. 42. Furthermore, an illustrative output 4300of the bandpass filter is shown in FIG. 43.

TABLE 2 Bandpass filter design specifications Type Optimal EquirippleOrder 296 (minimum order) Sample Frequency 250 MHz Fstop1 5 MHz Fpass1 7MHz Fpass2 15 MHz Fstop2 17 MHz Astop1 60 dB Apass (ripple) 0.3 dBAstop2 60 dB

Since classification of the nerve using only the scan line energy maynot yield satisfactory results, it is appreciated that a multivariateclassification approach can be explored. One commonly used multivariateclassification algorithm is a support vector machine (SVM). A SVM may bea supervised learning algorithm that attempts to find an optimallyseparating hyperplane between two labeled sets of data. Each observationwithin the data sets consists of a number of features, which may be insome aspects descriptive variables that may be used to help classify thedata.

For example, with reference to SVM classification schemes 4410 and 4420in FIG. 44, consider the two-dimensional classification problem below.The i^(th) observation in the training set is associated with a featurevector x^((i))=(x₁ ^((i)), x₂ ^((i))) and a data label y^((i))∈{−1,1}which describes the observation's class. Any hyperplane over the featurespace may be defined as {x:f(x)=β^(T)x+=β₀=0}, where β is a vector. Thegeneral goal of the SVM is to solve the optimization problem

$\min\limits_{\beta,\beta_{0}}{\beta }$

-   -   subject to the constraint y^((i))(β^(T) x^((i))+β₀)≥1

for all i in the training set. By solving this optimization problem, theSVM may locate the hyperplane which maximizes the margin betweenseparable data. Once the values for β and β₀ are found, new events maythen be classified based on which side of the hyperplane they lie, orequivalently:

ŷ(x)=sign(β^(T) x+β ₀)

This simple form of SVM works for separable data, like the case in FIG.44 on the left (e.g., scheme 4410). However, in many cases the data maynot be separable, such as the case on the right (e.g., scheme 4420). Inthis case, the SVM must change the optimization problem to include slackvariables, ξ_(i), into the optimization problem. The new optimizationproblem is then given by

${\min\limits_{\beta,\beta_{0},\xi_{i}}\; {\frac{1}{2}{\beta }^{2}}} + {C{\sum\limits_{i}\xi_{i}}}$such  that y^((i))(β^(T)x^((i)) + β₀) ≥ 1 − ξ_(i)

By adding these slack variables, the constraint is now much lessrestrictive, since the slack variables allow for particular data pointsto be misclassified. The amount of misclassification may be controlledby the reweighting factor C known as the box constraint. In someaspects, the box constraint may be a parameter specified by theoperator. When the box constraint is high, the optimization algorithmmay force the slack variables to be small, thus resulting in a morerestrictive classification algorithm.

Some classification problems do not automatically lend themselves tosimple linear decision boundaries. In these cases, a feature set may betransformed into a different domain before attempting linear separation.For example, the instances of x may be replaced with the transformedversion h(x). Typically these feature transformations are specified bytheir kernels. The kernel of the transformation is defined as the innerproduct between transformed feature vectors, or symbolically,

K(x ^((i)) ,x ^((j)))=

h(x ^((i)) ,h(x ^((j)))

A commonly used kernel may be the radial basis function or Gaussiankernel, which may have the form

${K( {x^{(i)},x^{(j)}} )} = {\exp ( {- \frac{{{x^{(i)} - x^{(j)}}}^{2}}{2\sigma}} )}$

In practice, Gaussian kernels are generally known to perform well innonlinear classification. However, Gaussian kernels also add anotherdegree of freedom to optimize over: the width parameter σ. This is yetanother parameter which may have to be tuned by the operator dependingon the target anatomy.

For each scan line, a set of features may be generated based on thestatistical information of the received RF data and envelopes. In orderto help mitigate corruption due to isolated strong scatterers,statistics based on the log of the envelope may also be computed. Theidentity and uniqueness of the classifier to the problem is thecombination of the feature set used to build the classifier. A completelist of features is given below. It is appreciated that for a particularembodiment, any combination of these features may be used for the SVM toidentify the target anatomy: (1) skewness of the received RF, (2) meanof the envelope, (3) variance of the envelope, (4) skewness of theenvelope, (5) kurtosis of the envelope, (6) mean of the log of theenvelope, (7) variance of the log of the envelope, (8) skewness of thelog of the envelope, (9) kurtosis of the log of the envelope.

FIG. 45 illustrates a plot matrix 4500 demonstrating that theabove-recited features do not appear to completely discriminate scanlines containing the nerve from scan lines that do not. Most of the datadoes not appear to follow a simple linear decision boundary, so aGaussian kernel with σ=1 was used to help preserve nonlinear tendencies.The box constraint parameter was also set to 1 during training.

To evaluate the performance of the SVM, an evaluation metric may becomputed by a specially-programmed computing device. In some aspects,the receiver operating characteristic may be used as an evaluationmetric. For example, as a classification algorithm, the ROC curve plotsthe true positive rate vs. false positive rate, thus displaying thedifferent trade-offs between operating at various threshold levels. FIG.46 illustrates the results 4600 of the ROC plot, indicating that theclassification algorithm appears to have good performance based on thetraining data distributions.

The testing demonstrated that a Gaussian-based SVM can be a powerfultool in determining the presence of the sciatic nerve in a single scanline. The majority of the power of any multivariate algorithm lieswithin the features used to describe the data. Utilizing just a singlescan line, the system may be able to achieve a true positive rate ofover 80% and a false negative rate of less than 10%.

Additional techniques contemplated include post-processing schemes, suchas time gain compensation, to accentuate deeper features in the tissue,or using filters such as median filters to remove some of the strongpeaks from the energy signals.

The detection of the nerve (or any other anatomical feature) may beautomated. Once the anatomical feature is detected, an audio or visualsignal such as “beeping” sound or a flashing light signal (or similarsignal) may be given to a physician to indicate that they, or thedevice, are within a certain distance from the nerve.

Automatic detection of nerve may be based on single scan lines, and maycompare the b-mode scan lines captured by the probe with the known scanlines of the target anatomy. In some aspects, the detection system maynotify the operator that the captured scan lines are identical to, orare within a certain predetermined value of, the known scan lines of thetarget anatomy (e.g., the known scan lines of the target anatomy mayrepresent a unique signature). The detection system may also becalibrated to determine the proximity of the tip of the probe to thetarget anatomy and notify the operator when the tip of the probe iswithin a set distance (e.g. 1 mm). Furthermore, the system may beconfigured to notify the operator of the spatial location of the targetanatomy and/or inversely the spatial location of non-target anatomy.

Further Details Regarding Aspects of the Present Disclosure

In some aspects, the device 10 may be equipped with an image capturesystem 200 as shown in FIGS. 29 and 30 used to detect certain portionsor aspects of the anatomy (e.g., nerve or vessels). The image capturesystem 200 may also be used independently of, or in conjunction with,the ultrasound imager 24, as described above in the device 10embodiments, and/or may be used as a stand-alone or a complimentarydetection technique to the ultrasound imager 24. In some aspects, thetip 22 in this embodiment may be a lens 23 that has an outer surface 202and an inner surface 204. It is appreciated that the outer surface 202of the lens 23 need not be the same shape of the inner surface 204 andmay differ depending on the desired optical performance. The lens 23 mayor may not provide a magnification of an image, I, beyond the lens 23.In this embodiment, the lens 23 provides no magnification. The lens 23in this embodiment is clear, but can also be tinted or provided with acolor filter as will be discussed below and may have anti-fog,anti-condensation, and/or anti-reflection coatings or properties.

As further seen in FIG. 30, the distal portion 14 of the device 10further includes the image capture system 200 having an image capturedevice 201. The image capture device 201 may include an image capturesensor 206 that is disposed adjacent to the distal end 20 of the mainbody 16. The image capture device 201 can be connected to a flexiblesheath 203 that may carry a fiber optic cable 205 that connects theimage capture device 201 to a housing 207 that houses the imageprocessing components. It is also contemplated that the image capturedevice 201 can be wirelessly coupled to the image processing components.

An image capture output device may be included that is in communicationwith an image control system that can adjust the properties of the imagequality. It can also be appreciated that the image capture device 201may wirelessly transmit images and video to the image control systemwithout any hard wired components. The term “image capture device” mayinclude devices configured to record or capture either still or videoimages, such as video cameras, digital cameras, CCD sensors, and thelike. One example of an image capture device that may be used with thedevice may be a 1/18″ CMOS camera with OMNIVISION sensor OV 6930.However, those skilled in the art will easily contemplate the settings &components such as the “image capture device,” illumination device, andthe like in accordance with the present disclosure as described herein.

In one aspect, the image sensor 206 of the image capture device 201 maybe disposed within the distal portion 14 of the main body 10. The imagesensor 206 or the capture device 201 may be at the most distal end 20 ofthe main body 16 such that it forms a distal surface 210 of the imagesensor 206 (or capture device 201) or is flush with the distal end 20 ofthe main body 16. In some aspects, “image sensor” may be synonymous with“image capture device.” In some aspects, the image sensor 206 may be setback proximally from the distal end 20 of the main body 16, depending onthe application. For example, the image sensor 206 may be recessed fromthe distal end 20 of the main body 16. Alternatively, the image sensor206 or the image capture device 28 may extend from the distal end 20 ofthe main body 16 towards the inner surface 204 of the tip 22.

The image capture device 201 may define an optical axis O. As shown inFIG. 30, the optical axis O is the axis collinear with the longitudinalaxis L defined by the main body 16 as discussed above. However, theoptical axis O may also be or offset from the longitudinal axis L. Theimage capture device 201 will have a field of view a, varying between 5and 180° depending on the specific application.

The image capture device 201 may be configured to capture an image Ithat exists just beyond the outer surface 202 of the tip 22.Specifically, as better shown in FIGS. 31 and 32, the tip 22 may beconfigured to dissect the anatomy of a patient, designated here aselement 212. As seen here, the tip 22 while dissecting the anatomy maycreate a working space 214 by way of its shape. This may enable theimage capture device 201 to view the anatomy during the dissectionprocess instead of having the anatomy directly abut the image capturedevice 201 which may distort the image quality.

In this embodiment, the working space 214 may be defined as the spacebetween the distal surface 210 of the image capture device 201 and theouter surface 202 of the tip 22. The working space 214 may permit theimage capture device 201 to view a portion of the anatomy that is withinits viewing angle α. Without the working space 214, the anatomy mightabut and thereby obstruct the image capture device 201 therebypreventing an illumination device 216 from illuminating the anatomy andthe image capture device 201 from capturing an image. The working space214 in some aspects may be primarily filled with air, but it can beappreciated that the working space may be filled with other materials,such as a liquid or other gases. In the alternative, the working space214 may be created by a tip that is solid such that the inner surface204 of the tip 22 is adjacent to the distal end 20 of the main body. Itcan be appreciated that the working space 214 may create a distancebetween the outer surface 202 of the tip 22 and the image capture device201 of 2 mm to 10 mm or greater

The distal portion 14 of the main body 16 may also include theillumination device 216, as shown in FIG. 33, which is a cross sectionalview of FIG. 30. The illumination device 216 may include a set of lightemitting diodes 218 (“LED”). It can be appreciated that the number ofLEDs 218 and the location of each LED 218 with respect to the imagecapture device 201 may vary. For the example, there may only be one LED218 for a particular application. Conversely, there may be as many asfour or more LEDs 218. In some aspects, the LEDs 218 are spacedequidistant from one other, but it is not a requirement and the LEDs 218may not be equally spaced. Other illumination devices 216 may include alight source such as near-infrared LED, mid-infrared LED, other LEDs ofvarious wavelengths ranging from UV to infrared, or any similar lightsource known in the art. The illumination device 216 may also take theform of a light source emitting from an annular ring around the imagecapture device 201 or a plurality of light fibers angularly spacedaround the image capture device 201

The illumination device 216 in the device 10 may be disposed within thedistal end 20 of the main body 16. However, the illumination device 216may be external to distal end 20 or tip 22 or be embedded in the tip 22such that the illumination device 216 does not create reflection on theinner surface 204 of the tip 22, as a reflection may impair the field ofvisibility of the image capture device 201. For example, and withoutlimitation, the illumination device 216 may be disposed on either sideof the longitudinal axis L of the main body 16 as shown in FIG. 34 anddistal from the distal end 20 of the main body 16

Regardless of the type of illumination device 216, the intensity of theillumination device 216 may be adjusted to as to change the level ofillumination of the anatomy of a patient. Moreover, if the illuminationdevice 216 includes more than one illumination sources, certain of theillumination sources may be turned off while others remain on, and thatthe intensity of each source may be independently adjusted.

The illumination device 216 may also include color filters to as tohighlight certain features of the patient's anatomy such as a nerve orvessel, through a filter. In some aspects where the illumination device216 consists of one or more LEDs 218, different color LEDs, such as redblue, yellow, green or others, may be used to enhance or highlightcertain features of a patient's anatomy. One alternative to placing thefilters with the illumination device 216 may be to include the filterswith image capture device 201. The filters may include color filters,including red, orange, yellow, green, magenta, blue, violet, and thelike. The filters may also include band pass-filters, such as UV, IR, orUV-IR filters to better view the desired anatomy. Alternatively, or inconjunction with the above, the illumination

device 216 may rely on ultraviolet to detect certain features of thepatient's anatomy, such as a nerve. In this embodiment, the illuminationdevice 216 may include a light source irradiating the desired portion ofa patient's anatomy with illumination light including excitation lightof a wavelength band in an ultraviolet or visible region. It is alsocontemplated that the illumination device 216 may have both illuminationmeans for emitting illumination light in the visible and ultravioletregions simultaneously and where the image capture device having anappropriate spectral response can capture images in both regions

The illumination device 216 may have an illumination axis IA asdisclosed in FIG. 35. The illumination axis IA may or may not becollinear with the optical axis O or the longitudinal axis L of thedevice. The illumination device 216 and location of the illuminationaxis IA may result in a reflection captured by the image capture device201 that may distort the image of the patient's anatomy. The reflectionmay be caused by the rays generated by the illumination device 216reflecting from an outer surface 202 or inner surface 204 of the tip 22or the lens 23. To minimize and/or eliminate the reflection caused bythe illumination device 216, the illumination axis IA may be displacedrelative to the optical axis O of the image capture device 201. In theaspect as shown in FIG. 35, the optical tip is shown as a solid lenswith the elliptical outside surface 202. One property of ellipticalsurfaces is that if a light source is placed at one focus, all lightrays on the surface of the ellipse are reflected to the second focus.Each of two light sources 216, in the form of LED or optical fiber, maybe placed at the focal point of elliptical surface 202. The illuminationrays 220 reflected from elliptical surface may concentrate at foci ofthis surface while the rays 222 reflected from the tissue abutting thesurface 202 may be directed toward the capture device 201. Thisarrangement eliminates the direct optical reflection of illuminationbeams into the image capture device 201 or sensor 206 while maintainingits on-axis position. The offset between the optical axis O and theillumination axis IA may vary in range including between 1 to 2.5 mm.

Another embodiment of the device that includes an offset between theoptical axis O and illumination axis IA is shown in FIG. 31. As shown inthis embodiment, the tip optical axis SO of the tip 22 is offset fromthe optical axis O of the image capture device 201 to reduce or minimizethe amount of reflection captured by the image capture device 201. Inthis embodiment, the illumination may be provided by an annular ring ofoptical fiber around the lens of the image capture device 201. Theillumination beams reflected from the inner surface 204 will focus onthe tip 22 center of curvature. Because the tip optical axis is offsetin relation to the optical axis of the image capture device 201 itscenter of curvature is outside of the objective field of view andtherefore reflected beams do not degrade the image quality.

As shown in FIGS. 36-37, the device 10 may also include a conduit 224disposed at least partially within the main body 16 and the tip 22. Inthe aspect shown in FIG. 36, the conduit 224 may be off-set from thelongitudinal axis L of the main body 16. However, in some aspects, theconduit 224 may be collinear with the longitudinal axis L of the mainbody 16. The conduit 224 may extend from the proximal end 18 of the mainbody 16, or may be formed along only a portion of the main body 16 andextend all the way through the distal portion 14 of the device,including the tip 22. The conduit 224 may be used in the ultrasound orvisualization embodiments of this device. The conduct 224 may also beplaced in the along the longitudinal axis of the main body 16, which mayrequire the transducer 26 to be offset to accommodate the conduit 224.

Stated differently, the location of the conduit 224 may vary and may beapplication dependent. For example, and without limitation, the conduitmay be placed closer to the longitudinal axis L than shown in theembodiment disclosed in FIG. 36. In the alternative, the conduit may beplaced on the exterior of main body 16 of the device to as to form araised portion that extends along a direction that is substantiallyparallel to the longitudinal axis L of the main body 16. In thisembodiment, the conduit 224 would reside in the raised portion as shownin FIG. 37, which is a cross-sectional view of the distal end 20 of themain body 16 of this embodiment.

In addition, it is contemplated that there may be more than one conduit224 for a particular device 10 thereby allowing an operator tosimultaneously place multiple instruments into the patient's anatomy.The diameter of the conduit is application dependent by can vary and maybe between 0.3 mm to 5.5 mm.

A conduit 224 as shown in FIGS. 36-37, may be configured to receive anumber of instruments, including a guide wire to guide the device 10through the anatomy of a patient, a k-wire to anchor the device 10 to asurgical site such as the disk space between two vertebra, anillumination device, such as an optical fiber, to provide additionalillumination to a particular region of the patient's anatomy, anultrasound probe to image or detect particular regions of a patient'sanatomy, such as the one described above, a fiber optic cord that emitsvisible or infrared light to image or detect particular regions of apatient's anatomy, a nerve stimulator for neuromonitoring, and the like.

In some embodiments, as shown in FIGS. 48 and 49, the device 10 may beprovided with a channel 4810 (hollow region) extending throughout thelength of the main body 16 and the tip 22. FIG. 48 shows the device 10,viewed from the distal end, to illustrate the tip 22 in theseembodiments. As shown in FIG. 48, the tip 22 may form an annulus orring. The inner space provided by the channel 4810 may provide a workingchannel inside the device 10 through which a surgeon may performclinical procedures while allowing the device 10 to remain in place.This may allow for the collection and display of data for real-timefeedback form the site of the surgery during the surgical procedure. Inaspects of these embodiments, the main body 16 and the tip 22 mayprovide a channel 4810, with a diameter in a range from 24 mm to 40 mm.The wall of the main body 16 and/or tip 22 may be 10 mm in width.Various other diameters and widths are contemplated herein; the valuesdiscussed above are examples to aid in understanding of the disclosure.For example, in some embodiments, the diameter of device 10 may beselected to allow a particular surgical implement to be fitted throughthe channel of device 10 so that imaging may continue as the implementis advanced into tissue. In various aspects, the channel 4810 may beoff-set from the longitudinal axis of the main body 16. However, in someaspects, the channel 4810 may be collinear with the longitudinal axis ofthe main body 16. The channel 4810 may extend from the proximal end 18of the main body 16 all the way through the distal portion 14 of thedevice 10, including the tip 22.

In these embodiments, multiple transducers 26, such as transducer 4810of FIG. 48, may be arranged on the distal end 20 of the device 10, onthe ring-shaped tip 22. As discussed above, the transducers 26 may emitan ultrasonic frequency in a direction that is substantially parallel tothe longitudinal axis of the device 10. It is also contemplated thatvarious transducers may emit an ultrasonic frequency in a direction thatis not parallel to the longitudinal axis of the device 10. It can beappreciated that the transducers 4820 may be orientated in any directionthat is required for the particular application. The ultrasonicfrequency may be between 1 and 10 MHz, depending on the application. Theultrasound imager 24 may collect information, such as acoustic propertyresults, from the transducers and, using the classification algorithm,screen for target tissue, such as nerve tissue. Nerve tissue may behighlighted on a display. In some embodiments, a 2-D mapping or a 3-Dvisualization (e.g. volumetric image) of nerve tissue may be generatedand displayed.

In some embodiments, as shown in FIG. 49, the device 10 may have alength of 120 mm to 150 mm, forming the shape of a tube 4910. It iscontemplated that the device 10 may have a variety of other lengths,depending on the application. Probe 4920 is an example of a surgicaltool that may be passed through the channel 4930 for various surgicalprocedures.

FIG. 50 shows the distal face of the tube, in order to illustratevarious embodiments. The transducers are contemplated to have variousshapes, such as a square, a rectangle, such as the rectangulartransducers 5010, and circular, such as the circular transducers 5010.In some embodiments, more than one row of transducers may be arranged onthe distal face, as illustrated in image 5030. Various quantities oftransducers may be used, depending on the application. In someembodiments, 100 to 250 or more transducers may be position on thedistal end of the tube. Transducer frequency may be in the range of 5MHz to 20 MHz to cover the appropriate depth required for theapplication (for example, 0.1-5 cm in depth). Other transducerfrequencies may be used in various embodiments.

The above embodiments may be further understood by referring to FIGS.51-54. FIG. 51 shows the views 5110 and 5120 of device 10 having thechannel as described above. Image 5130 shows the device 10 placed on thesurface of the psoas muscle. The placement of the device 10 on thesurface of the psoas muscle may be a first step prior to entering thepsoas muscle in order to allow the surgeon to visualize the location ofnerves within the psoas muscle using the methods as described herein.The transducers may emit ultrasound signals around the distal end of thedevice 10 and the image processor/software may form an image with adepth of 5-7 cm, creating a 3-D “volumetric” image of the area in thepsoas muscle overlying the vertebral body and disc space. Based on useof the classification algorithm, sensory and motor nerves, and theirrouting, may be highlighted on the display.

FIG. 52 shows the device 10 and a surgical probe 5210. Image 5220 showsthe device 10 placed into position on the surface of the psoas muscle.Image 5230 depicts the probe 5210 before it is placed into the channelof device 10, which is in position on the psoas muscle. FIG. 53 depictsthe device 10, placed against the psoas muscle 5140 and with the probe5210 inserted (retracted) into the channel of device 10. At this point,the device 10 is in position for performing the operations as describedherein to map the nerve tissues in the psoas muscle. FIG. 54 depicts thedevice 10, placed against the psoas muscle 5140 and with the probe 5210inserted into the channel of device 10 and into the psoas muscle. Image5400 shows an example anatomical image with a viewing window 5410 as maybe generated by use of the classification algorithm. The viewing window5410 may depict a map of the nerve tissues in the psoas muscle proximateto the device 10.

Various aspects of the present disclosure are contemplated for beingused in connection with minimally invasive surgery (MIS). The device 10may be used for a variety of MIS procedures, including but not limitedto, a lateral retroperitoneal interbody fusion (LLIF) (e.g., XLIF,DLIF), Axial Lumbar Interbody Fusion (AxiaLif), Transforaminal LumbarInterbody Fusion (TLIF), Posterior Lumbar Interbody Fusion (PLIF),Anterior Lumbar Interbody Fusion, Trans-thoracic lumbar interbodyfusion, Retropleural Thoracic Fusion, Interbody Fusion utilizingKambin's Triangle, and Cervical/Thoracic/Lumbar Laminectomies,Foraminotomies and Diskectomies. The device 10 may be used to confirmthat the area is clear of other anatomical parts, such as blood vessels,abdominal/pelvic viscera, nerve roots, and spinal cord. As shown in FIG.19, once at the surgical site 46, the device 10 may be used toilluminate the surgical site 46, to allow a surgeon to introduceinstruments (e.g. K-wire) to the surgical site via a conduit formedwithin the main body 16 of the device 10 or allow a retractor system ordilator system to create direct visualization and a working portal ofthe surgical site without the device 10.

As described above, there can be a number of applications for which thisdevice 10 may be used, which require the similar steps to access thesurgical site. The method of use described below is in connection withperforming an LLIF, but it can be appreciated that the device 10 can beused in a similar fashion for performing other MIS procedures asmentioned above.

In operation, the ultrasound imager 24 is used to detect the patient'sanatomy as described herein. A surgeon may rely on the image or audioqueues generated by the ultrasound imager 24 to detect the presence (orabsence) of a nerve thereby allowing the surgery to reposition (orcontinue advancing) the device 10 through the patient's anatomy towardsthe surgical site 46. The ultrasound imager 24 may also be used toconfirm the image captured by an image capture device (not shown) isaccurate by confirming the presence or absence of a targeted anatomicalfeature (e.g. nerve). The image capture device may consist of a cameraor the like disposed within the distal portion 14 of the device 10 so asto capture an image of the region distal to the device 10.

The image capture system 200 may also be used in a similar fashion tovisually detect the patient's anatomy. The image capture system 200 maybe used to confirm what is detected by the ultrasound imager 24, or maybe used independently to detect certain portions of the patient'sanatomy.

The classifier/algorithm is integral in accurate nerve detection. In analternative embodiment of the present invention, the classifieralgorithm may be employed as follows:

An ultrasound probe acquires ultrasound backscatter data via a sectorscan or similar ultrasound acquisition mode.

A 2D B-mode image may be constructed from the acquired data. A 2D B-modeimage may be constructed using known methods and techniques. In oneembodiment, a 2-dimensional image may be built up by firing a beamvertically, waiting for the return echoes, maintaining the informationand then firing a new line from a neighboring transducer along atambourine line in a sequence of B-mode lines. In a linear array ofultrasound crystals, the electronic phased array may shoot parallelbeams in sequence, creating a field that is as wide as the probe length(footprint). A curvilinear array may have a curved surface, creating afield in the depth that is wider than the footprint of the probe, makingit possible to create a smaller footprint for easier access throughsmall windows. This may result in a wider field in depth, but at thecost of reduced lateral resolution as the scan lines diverge.

The image may be thresholded such that image intensity values above thethreshold may be given a value of ‘1’ and image intensity values lessthan the threshold may be given a value of ‘0’. This may result in abinary map of intensity values.

The binary image may then be filtered with a smoothing filter which mayconsist of a simple median filter or similar smoothing filter. It iscontemplated that a variety of digital filters may be employed toprocess the binary image.

The numbers of pixels for contiguous regions in the binary image may becounted.

Contiguous regions in the binary image that have a pixel count above aminimum threshold and below a maximum threshold may be selected. Thismay correspond to areas of contiguous regions in the binary image. Thethresholds may be selected so that a nerve in the image will be detectedand selected with a high degree of accuracy.

If the selected contiguous regions are less than a specified distancefrom the probe (2 cm, for example), the contiguous region may beselected as a possible nerve. It should be understood that the measureddistance may be within a range of distances, and that the specificdistance of 2 cm is provided by way of example.

A shape factor may next be implemented by fitting an ellipse to outlinethe selected contiguous regions in the 2D binary image. The area of thecontiguous region may be compared to the area of the ellipse outliningthe contiguous region. If the ratio of the areas is below a certainthreshold, the contiguous region may be classified as not a nerve. Avariety of outlining techniques, aside from the fitting of an ellipse,may be used to compare the contiguous region.

If the contiguous region is classified as a nerve, the original imagedata corresponding to the contiguous region may next be processed fortexture features. Specifically, for the selected contiguous region, theSNR, kurtosis and skewness may be calculated from the B-mode image data(it is understood that alternative data parameters may be measured atthis time as well). Threshold values for each of these parameters may beestablished in order to detect the nerves in the image. If thecombination of the SNR, skewness and kurtosis are below a threshold, thecontiguous region will be classified as not a nerve. It is contemplatedthat additional data parameters may be measured from the original imagedata for nerve detection.

In an alternative embodiment, robust detection using double thresholdand connected component tracking by hysteresis may be employed.Specifically, instead of using only one, it may be preferred to use twothreshold values: a high threshold value and a low threshold value. Foreach pixel in the B-mode image, if its value is larger than the highthreshold value, then it may be marked as a strong nerve pixel. If thepixel value is smaller than the high threshold value and larger than thelow threshold value, then it may be marked as weak nerve pixel. If thepixel value is smaller than the low threshold value, then it may bediscarded. The connected component algorithm may be applied to look ateach weak nerve pixel, and if it is connected to a strong nerve pixelthen the weak nerve pixel may be preserved.

In some embodiments, the shape of the identified connected components(blobs) of detected nerve pixels may then be analyzed. If the size andshape of a blob is significantly different from the profile of a nervearea (elongated or elliptical of width about 5 mm) then it may alsodiscarded. The detected nerve region in a B-mode image should have, atmost, a maximum dimension of 1 or 2 cm. It is understood that data mayfall in ranges which may yield the detection of a nerve, and thatspecific numbers are only provided by way of example.

The distance from the detected nerve region to the ultrasound probe maybe estimated and used in the display.

In an alternative embodiment of the present invention, it iscontemplated that sophisticated training and detection algorithms fornerve region like support vector machine (SVM) or random forest may beutilized for improved nerve detection. In machine learning, supportvector machines (also support vector networks) may be supervisedlearning models with associated learning algorithms that analyze dataand recognize patterns, used for classification and regression analysis.Given a set of training examples, each marked as belonging to one of twocategories, an SVM training algorithm may build a model that assigns newexamples into one category or the other, making it a non-probabilisticbinary linear classifier. An SVM model is a representation of theexamples as points in space, mapped so that the examples of the separatecategories are divided by a clear gap that is as wide as possible. Newexamples may then be mapped into that same space and predicted to belongto a category based on which side of the gap they fall on. In additionto performing linear classification, SVMs can efficiently perform anon-linear classification using what is called the kernel trick,implicitly mapping their inputs into high-dimensional feature spaces.Random forests are an ensemble learning method for classification,regression and other tasks, that operate by constructing a multitude ofdecision trees at training time and outputting the class that is themode of the classes (classification) or mean prediction (regression) ofthe individual trees. Random forests correct for decision trees' habitof overfitting to their training set. Decision trees are a popularmethod for various machine learning tasks. Tree learning comes closestto meeting the requirements for serving as an off-the-shelf procedurefor data mining because it is invariant under scaling and various othertransformations of feature values, is robust to inclusion of irrelevantfeatures, and produces inspectable models. However, they are seldomaccurate. In particular, trees that are grown very deep tend to learnhighly irregular patterns: they over fit their training sets, becausethey have low bias, but very high variance. Random forests are a way ofaveraging multiple deep decision trees, trained on different parts ofthe same training set, with the goal of reducing the variance. Thiscomes at the expense of a small increase in the bias and some loss ofinterpretability, but generally greatly boosts the performance of thefinal model.

Once the muscles are split and the surgical site 46 is reached, thesurgeon can place a k-wire through the conduit to confirm that thesurgical site 46 is reached and anchor the device 10 with respect to thesurgical site 46. A retractor tool 48 may be put into place to give thesurgeon a direct surgical working conduit to the surgical site 46.Alternatively, a series of dilators may be sequentially placed over themain body 16 to create the working space. Once this direct access to thespine is achieved, the surgeon is able to perform a standard discectomy(removing the intervertebral disc), corpectomy (removing the vertebralbone) or fusion (uniting two bones together) with surgical tools.

An embodiment of the retractor system 48 may include a first blade 49and a second blade 51, both of which may be semi-circular in shape thatform an opening that fits snugly around the outer diameter the main body16. It is appreciated that the cross-sectional shape of the blades canmimic the shape of the main body 16 (e.g., triangular, oval, square,rectangular, etc.). Once at the surgical site, the retractor blades 49,51 may be configured to separate relative to one another so as to expandthe dissection and to enable the device 10 to be removed and allow fordirect visualization of the surgical site 46 as shown in FIG. 19. It iscontemplated that the distal ends 53 of the first 49 and second 51blades are adjacent to the distal portion 14 of the main body 16. Anyknown type retractor system may be used with the device 10.

In one embodiment, a retractor system 226, like the one disclosed inFIG. 38, may be disposed over the device 10 and configured to expand tocreate a working space within the anatomy of the patient once a surgicalsite, or other location where a surgical procedure is to take place, isreached. This embodiment of the retractor system 226 includes a firstblade 228 and a second blade 230, both of which are semi-circular inshape that form an opening that fits snugly around the outer diameterthe main body 16. Once at the surgical site, the retractor blades 228,230 are configured to separate relative to one another to expand thedissection so as to enable the device 10 to be removed and allow fordirect visualization of the surgical site 68 as shown in FIG. 38. Thedistal ends 232 of the first 228 and second 230 blades may be adjacentto the distal portion 14 of the main body 16. Any type known retractorsystem may be used with the device 10. It can be appreciated thatstimulation electrodes, visualization cameras and illumination devices(optical, ultrasound, infrared and ultraviolet) may also be placed alongor within the retractor blades 228, 230 so as to allow for nervedetection as discussed above

As shown in FIG. 39, a cross-sectional view of the

retractor 226 disposed around the device 10, the main body 16 of thedevice 10 may have a raised channel or channels 234 disposed along itslength in a direction along the its longitudinal axis that is configuredto slidingly receive a complimentary groove 236 formed by the first andsecond blades 228, 230 of the retractor system 226. In some aspects, theraised channel 234 and/or groove 236 may have a square, rectangle,semi-spherical or a similar cross-sectional shape. Further, the numberand location of the channel 234 and groove 236 may vary. For example,but without limitation, the may only be one channel/groove running alongthe main body 16.

Alternatively, there may be more than two channels/grooves that areequidistantly placed about the outer surface of the main body 16. Thechannel and groove may also be transposed, such that the grove 236 is onthe main body 16 and the raised channel 234 is formed along the blades228, 230, as shown in FIG. 40, such that the groove 236 prevents theblades 228, 230 from expanding when the retractor 226 is disposed overthe device 10. The channel 234 and groove 236 may extend along only aportion of the main body 16 of the device 10 and the blades 228, 230.

The retractor system 226 may consistent of multiple sets of blades 228,230 with varying thickness and diameter. For example, and withoutlimitation, the blades 228, 230 may vary in size so as to have anoverall outer diameter ranging from 2 mm to 80 mm when in the closed(e.g., collapsed) configuration. Further, the blades 228, 230 may beconfigured such that they create a 2 mm to 220 mm opening within thepatient's body when in the expanded configuration. The device 10 andretractor system 226 may be configured such that a first set of blades228, 230 having a larger retracted diameter may be used to create afirst opening within the patient's body and then a second set smallerdiameter blades having a retracted diameter that is different than thefirst set of blades 228, 230 may be slidingly disposed over the mainbody 16 and within the first opening and retracted to open a secondopening within the patient's body at a location distal to the firstopening. The openings created by the first and second set of blades mayhave different opening diameters. The retractor system 226 may allow theoperator to create multiple openings having different retracteddiameters at different anatomic levels within the patient. A lightsource (not shown) may be disposed at the distal ends, or along thelength, of the blades 228, 230 to illuminate the opening within thepatient's body and illuminate the region of the patient's anatomy withinand distal to the opening created by the blades 228, 230 In addition, aconduit (not shown) may also be formed within the blades so as toreceive one or more of: a medical instrument, such as a k-wire to anchorthe blades 228, 230 to a surgical site such as the disk space betweentwo vertebra; an illumination device, such as an optical fiber, toprovide additional illumination to a particular region of the patient'sanatomy; an electrical conduit to provide neural stimulation; aultrasound probe to image or detect particular regions of a patient'sanatomy; a image capture device; a fiber optic cord that emits visibleor infrared light to image or detect particular regions of a patient'sanatomy; and the like. The blades 228, 230 may be made out of anypreferable surgical grade material, including but not limited to,medical grade polymer including PEEK (polyether ether ketone), and maybe transparent (e.g. made out of clear plastic) or translucent.

In another embodiment, the retractor system 226 may be integrated withthe device 10 such that it forms part of the main body 16 and can bedeployed once at the surgical side. The retractor system 226 in thisembodiment may expand radially away from the longitudinal axis of themain body 16 to expand the path created by the main body 16. The mainbody 16 may then be withdrawn from the surgical site so as to create aworking portal within the retractor system 226.

A series of dilating cannulas (e.g. dilators 100), as shown in FIG. 20,may also be slidingly placed around the main body 16 of the device 10 soas to expand the diameter of the dissection made by the distal portion14 of the device 10. The technique of employing a series of dilatingcannulas to create a working space for direct visualization used inother medical procedures to create a working space may also be used inconjunction with the device 10.

After disc material is removed, the surgeon may be able to insert animplant/spacer through the same incision from the side. This spacer(cage) may help hold the vertebrae in the proper position to make surethat the disc height (space between adjacent vertebral bodies) iscorrect and to make sure the spine is properly aligned. This spacer,together with a bone graft, may be designed to set up an optimalenvironment to allow the spine to fuse at that particular segment. Thesurgeon may use fluoroscopy to make sure that the spacer is in the rightposition. The surgeon may then remove the refractor and suture anyincisions.

Spinal surgeons oftentimes access the intervertebral disc space andvertebral body via a transpsoas approach. The transpsoas muscle howeverhas a network of nerves (lumber plexus) within the muscle and theirexact location can be unpredictable The surgeon must therefore get tothe disc while avoiding these nerves so as not to cause nerve damage orparalysis when performing surgery The present disclosure allows thesurgeon to visualize where nerves lie before penetrating the psoasmuscle. The device 10 and the classification algorithms may be used tocreate a quantitative image and/or map (2D or 3D) of the nerve tissuewhile the device 10 is placed above the psoas, providing a surgeon apath that avoids nerves and gets to the disc space. In some embodiments,a mapping of target tissue proximate to the surgical site may beprovided by the ultrasound imager 24. When the tip 22 is disposedadjacent to the psoas muscle, the surgeon may slide a first set ofblades of the retractor system over the device and expand the retractorsystem 48 to create a first working space (also referred to as asuperficial dock). This working space may allow the surgeon to visuallyinspect the psoas muscle and the surrounding region either via naked(eye) inspection or with the optical camera/dissector (e.g., one or morecomponents of device 10). Next, the surgeon may continue the procedureby using the device, which is now disposed within the first workingspace to dissect through the psoas muscle as described herein. Once thetip 22 has reached the surgical site, which is the disc space here, asecond set of retractor blades which are smaller than the first set ofblades may be slid over the device 10 and expanded to create a secondworking space that is smaller in diameter than the first working space.The surgeon may then continue with the procedure in the manner discussedherein. One benefit of establishing the first working space may be thatit allows the surgeon to remove the device 10 from the surgical siteonce the procedure is completed at the first surgical site andreposition and reinsert the distal tip 22 of the device 10 within thefirst working space that is formed above the psoas muscle at a secondlocation to allow the surgeon to penetrate the psoas muscle to reach asecond surgical site to conduct and complete another procedure or amulti-level procedure in which psoas dissection is currently dangerousbecause of the interposed neurovascular structures (L3-4 and L4-5 discspace or a lumbar corpectomy—removal of two discs and the interveningbone). It is appreciated that the tip 22 is optional and the distal end21 of the device 10 maybe the portion of the device that is advancedtowards the surgical site.

In some embodiments employing the device 10 having the channel 4930,when the tip 22 is disposed adjacent to the psoas muscle, the surgeonmay position surgical tools/implants through the channel 4930 to accessthe surgical site while allowing the transducer(s) to collect data forreal-time display. By allowing the surgeon to perform surgery while thedevice 10 is in place, the transducer can record and collect datathroughout the surgery. The device 10 may also serve as a retractor oftissue, thereby pushing surrounding tissue to the side and assistingwith creating the working portal for the surgeon. Once the tip 22 hasreached the surgical site, the surgeon may continue the use of toolsthrough the channel 4930 or may employ a second set of tools, such asretractor blades, over the device 10. The surgeon may then continue withthe procedure in the manner discussed herein.

The device 10 may also be used for performing an axial lumbar interbodyfusion (AxiaLIF). At surgery, the patient may be positioned prone withmaintenance of lordosis and the legs spread. A catheter may be insertedinto the rectum will allow air to be injected during the procedure forvisualization of the rectum. After the surgeon makes a small incision(15-18 mm) lateral to the tip of the coccyx, the distal tip 22 of thedevice 10 may be inserted through the incision and is passed into thepre-sacral space. The surgeon may use the distal portion 14 of thedevice 10 to sweep and scan the pre-sacral space to confirm that thespace is clear of any offending anatomy (e.g. colon, rectum). The device10 may be gently passed along the anterior cortex of the sacrum and inthe midline to an entry point usually close to the S1-2 junction. Oncethe trajectory is chosen, a sharp beveled pin may then be driven intothe L5-S1 interspace, either through the conduit 36 or after theretractor system 48 is deployed. The retractor system, 48 or a series ofdilators may be used to create approximately a 10 mm opening into thesacrum through which a 10 mm channel is drilled into the L5-S1 disc. Thedevice 10 may then be withdrawn from the pre-sacral space and thesurgeon may then perform the remaining steps of the AxiaLIF procedure.

The device 10 may also be used to allow direct access to Kambin'striangle (ExtraForaminal Lumbar Interbody Fusion). For this procedure,patients may be placed in a prone position, typically onto a JacksonTable using a radiolucent frame that allows for restoration of lumbarlordosis. Fluoroscopic imaging may be utilized to identify theepiphyseal plate of the upper and lower vertebral body by controllingthe cranial-caudal angle of the image intensifier. Additionally, thefluoroscopic image may be rotated by 20-35 degrees toward the region, sothat the superior articular process may be seen at the middle of theintervertebral disc. At this location, the tip 22 of the device 10 maybe inserted percutaneously targeting the area commonly referred to asKambin's triangle. Kambin's triangle is defined as the area over thedorsolateral disc. The hypotenuse is the exiting nerve root, the base(width) is the superior border of the caudal vertebra and the height isthe dura/traversing nerve root. FIG. 55 depicts a visual representationof Kambin's triangle 5500. FIG. 56 shows the device 10 in a positiontargeting Kambin's triangle, as described above.

The device 10 may also be used to ultrasonically identify variousanatomical features such as the exiting root, radicular artery, thecalsac and the disc space. A k-wire can then be place into the disc spacevia the conduit 36 under ultrasonic detection via the device 10 allowingfor docking of the dissector/retractor system 48. Subsequent dilationcan then be performed allowing for access in the intervertebral foramenwhile directly visualizing neurovascular structures using the device andavoiding these structures when identified by the surgeon.

The device 10 may also be used in treatment of extraforaminal discherniations, such as in procedures involving extraforaminalintervertebral fusion. A far lateral discectomy is a commonly performedprocedure for the treatment of extraforaminal disc herniations. It isroutinely done through a paramedian incision using the Wiltse plane.However, the exiting nerve root (i.e. the L04 nerve root at the L45level, see FIG. 48) is at risk of damage with this approach, as it isnormally draped over the disc. In order to decrease the risk of nerveinjury, some surgeons currently use intraoperative nerve monitoring;however, intraoperative nerve monitoring relies on advanced anestheticthat may not allow for relaxation of the patient. Recently, surgeonshave considered use of interbody cage in intervertebral fusionapproaches through the far lateral extraforaminal approach. While thereare advantages to a muscle and bone sparing approach to intervertebralfusion, the passage of an interbody cage device into the disc spaceincreases the risk to the exiting nerve as well as the nerves that haveexited from proximal levels and are running under the intertransversemembrane. In order to safely perform an extraforaminal intervertebralfusion, we disclose herein use of the device 10 for performing detectionof the neurologic structures that run under the intertransverse membraneas well as the exiting nerve root as it is leaving its foramen. Once thenerve is detected, the device 10 can be safely docked on the far lateralportion of the disc, just anterior to the pars interarticularis.Dilators may then be advanced over the main body 16 of the device 10 andthen a tubular retractor may be docked on the disc, just anterior to thepars interarticularis and in between the transverse processes of the twoinvolved vertebrae. Once the retractor is safely docked, the surgeon mayproceed with preparation of the disc space and endplates and safelyinsert the intervertebral cage for fusion.

FIG. 57 depicts a skin incision made approximate 5-6 cm lateral to themidline, according to the methods disclosed herein. The incision may becentered lateral to the facet-pedicle junction. FIG. 58 shows thenatural cleavage plane, between the multifidus part of the sacrospinalisand the longissimus part, as may be used for spinal approach in someembodiments. This plane allows direct access to the pars, transverseprocesses and facet joints with minimal soft tissue dissection andretraction. This approach is less vascular than the mid-line approach,and therefore may result in less bleeding.

In another embodiment, shown in FIG. 21, an ultrasound imager 24 may beused in conjunction with a glove 110. In this embodiment, the operatormay rely on tactile feedback provided by touch while still enablingultrasonic imagining/scanning of a patient's anatomy. More specifically,the glove system (or device) may allow for tactile feedback thatfacilitates the dissection and separation of tissue namely neurological,vascular and peritoneal structures. In general, tactile feedback allowsfor dissection of tissue in normal surgical procedures without theunique perspective of direct visualization that may not be permissiblein some minimally invasive/percutaneous techniques.

The ultrasound imager 24 may include a transducer 26 that is configuredto emit sound waves may be disposed at the distal end of the glove 110.In one embodiment, the transducer 26 is located along a distal portion114 of the index finger 112 of the glove 110. As better shown in FIG.22, a

tip 22 forms part of, or is connected to, the distal portion 114 of theindex finger 112 such that the outer surface 24 of the tip 22 does notextend beyond the very most distal part of the index finger 112. Ofcourse, it is appreciated that the tip 22 may extend beyond the distalportion depending on the embodiment.

Connected to the transducer 26 may be a flexible conduit 116 that maycarry a cable that connects the transducer 26 to a housing that containsthe remaining portion of the ultrasound imager 24. The flexible conduit116 may run along the length of the index finger 112 and a top portion118 of the glove 110. However, it can be appreciated that the conduit116 can run along any length or surface of the glove 110 and isapplication dependent. The flexible conduit 116 may also provide achannel to carry a k-wire or other instrument that can be slidinglydisposed within the flexible conduit 116 (as will be further discussedbelow). The flexible conduit 116 may run through and may be incommunication with a unit 109 such that a portion of the flexibleconduct 116 provides an opening 120, as shown in FIG. 23, in the unit109 at the distal portion 114 of the index finger 112.

The unit 109 may have a bottom portion 122, as shown in FIG. 23. Thebottom portion 122 may have a concave curvature so as to provide acomplimentary fit once an operator's hand is placed within the glove110. In addition, a proximal portion of the unit 109 may have a taper soas to cause minimal disruption to a patient's anatomy as the unit 109 isarticulated during a procedure. Further, the unit 109 may have anoverall semi-circular or cylindrical shape or the like so as to minimizeany inadvertent disruption to the patient's anatomy during a procedureand to maintain a small overall profile as shown in FIGS. 24 and 25. Forexample, the height of the unit 109 may be less than the overall widthto as to achieve a low profile. Alternatively, the outer portion of theunit 109 may not extend beyond and become collinear with the width ofthe index finger 112 to maintain a low profile. The external outerdiameter of the unit 109 may range from 0.5 to 20 mm and outside of thisrange depending on the desired application. The length of the unit 109can range from 0.5 to 10 mm but also may fall outside of this rangedepending on the application. It is appreciated that more than onetransducer 26 may be positioned along the distal portion of a fingersuch that they provide side facing scans to generate a multi-directional(e.g. 180°-300°) scan of the patient's anatomy.

Transducers 26 may be side positioned (e.g. on either side of the indexfinger 112) so as to provide for multi-directional scanning of thepatient's anatomy to detect the nerve or target anatomy. The sidepositioned transducers may be configured to scan the anatomy around in acircumferential direction around the index finger 112 to detect thenerve (or other target anatomy) not detected by the transducerpositioned at the distal end of the main body 16. The multi-directionalscanning may enable the system to generate a scan image of the patient'sanatomy in multiple directions as the index finger 112 of the glove 110is advanced through the patient's anatomy. As discussed above, thesystem that is in communication with the transducers may then detect thenerve even that is not captured by the forward scanning transducer.

The image capture system 200, as discussed in relation to FIGS. 29 and30, may be used with the glove embodiment where the image capture device201, its tip 22, sensor 206, and illumination device 216 may be placedon a distal portion 114 of the index finger 112 of the glove 110. Theimage capture system 200 may also be used independently of, or inconjunction with, the ultrasound imager 24 as described above in theglove embodiments.

The glove embodiment can be used in connection with minimally invasivesurgery (MIS). The glove 110 may be used for a variety of MISprocedures, including but not limited to, Lateral RetroperitonealInterbody Fusion (LLIF (e.g., eXtreme Lateral Lumbar Interbody Fusion(XLIF), Direct Lateral Interbody Fusion (DLIF)), Axial Lumbar InterbodyFusion (AxiaLif), Transforaminal Lumbar Interbody Fusion (TLIF),Posterior Lumbar Interbody Fusion (PLIF), Anterior Lumbar InterbodyFusion, Trans-thoracic lumbar interbody fusion, Retropleural ThoracicFusion, Interbody Fusion utilizing Kambin's Triangle, andCervical/Thoracic/Lumbar Laminectomies, Foraminotomies and Diskectomies.The glove 110 may be used to confirm that the area is clear of otheranatomical parts, such as blood vessels, abdominal/pelvic viscera, nerveroots, and spinal cord.

As described above, there can be a number of applications for which thisglove 110 may be used, which may require similar steps to access thesurgical site. The surgeon may rely on the image or audio queuesgenerated by the ultrasound imager 24 to detect the presence (orabsence) of a nerve thereby allowing the surgery to reposition (orcontinue advancing) the glove 110 through the patient's anatomy towardsthe surgical site 48.

Once the muscles are split and the surgical site 48 is reached, thesurgeon can place a k-wire through the conduit to confirm that thesurgical site 48 is reached and anchor the glove 110 with respect to thesurgical site 48. A retractor tool is put into place to give the surgeona direct surgical working conduit to the surgical site 48.Alternatively, a series of dilators may be sequentially placed over thek-wire to create the working space. Once this direct access to the spineis achieved, the surgeon is able to perform a standard discectomy(removing the intervertebral disc), corpectomy (removing the vertebralbone) or fusion (uniting two bones together) with surgical tools.

In the case of a discectomy, after the disc material is removed, thesurgeon may be able to insert an implant/spacer through the sameincision from the side. This spacer (cage) will help hold the vertebraein the proper position to make sure that the disc height (space betweenadjacent vertebral bodies) is correct and to make sure the spine isproperly aligned. This spacer, together with a bone graft, may bedesigned to set up an optimal environment to allow the spine to fuse atthat particular segment. The surgeon may use fluoroscopy to make surethat the spacer is in the right position. The surgeon may then removethe refractor and suture the incisions.

The glove system may also be used for performing an axial lumbarinterbody fusion (AxiaLIF). At surgery, the patient may be positionedprone with maintenance of lordosis and the legs spread. A catheter maybe inserted into the rectum will allow air to be injected during theprocedure for visualization of the rectum. After the surgeon makes asmall incision (15-18 mm) lateral to the tip of the coccyx, the distalportion of the index finger 112 and distal tip 22 is inserted throughthe incision and is passed into the pre-sacral space. The surgeon mayuse the index finger 112 to sweep and inspect the pre-sacral space toconfirm that the space is clear of any offending anatomy (e.g. colon,rectum) visually and by way of ultrasonic imaging. The index finger 112may be advanced along the anterior cortex of the sacrum and in themidline to an entry point usually close to the S1-2 junction. Once thetrajectory is chosen, a sharp beveled pin may then be driven into theL5-S1 interspace, either through a conduit or after the retractor systemis deployed. The retractor system or a series of dilators may be used tocreate approximately a 10 mm opening into the sacrum through which a 10mm channel is drilled into the L5-S1 disc. The index finger 112 may thenbe withdrawn from the pre-sacral space and the surgeon may then performthe remaining steps of the AxiaLIF procedure.

The glove system may also be used to allow direct access to Kambin'striangle (Extraforminal interbody fusion). For this procedure, patientsmay be placed in the prone position typically onto a Jackson Table usinga radiolucent frame that allows for restoration of lumbar lordosis.Fluoroscopic imaging may be utilized to identify the epiphyseal plate ofthe upper and lower vertebral body by controlling the cranial-caudalangle of the image intensifier. Additionally, the fluoroscopic image maybe rotated by 20-35 degrees toward the region, so that the superiorarticular process can be seen at the middle of the intervertebral disc.At this location, the index finger 112 can be inserted percutaneouslytargeting the area commonly referred to as Kambin's triangle. Asdiscussed above, Kambin's triangle is defined as the area over thedorsolateral disc. The hypotenuse is the exiting nerve root, the base(width) is the superior border of the caudal vertebra and the height isthe dura/traversing nerve root.

The glove system may be used to identify various anatomical featuressuch as the exiting root, radicular artery, thecal sac and the discspace. A k-wire can then be place into the disc space via the conduitunder ultrasonic visualization allowing for docking of thedissector/retractor system. Subsequent dilation can then be performedallowing for access in the intervertebral foramen while directlyvisualizing neurovascular structures using the device and avoiding thesestructures when identified by the surgeon.

The device 10 may also include infrared technology, which includes aninfrared emitting light source and an infrared image capture device. Thedevice 10 may include one or more infrared radiation detecting elementsmounted at the distal portion 14 of the device 10. The infrared arraymay be sensitive at e.g. wavelengths from 2 to 14 micrometers. Oneembodiment of the infrared aspect of the present disclosure uses atwo-dimensional array of microbolometer sensor elements packaged in anintegrated vacuum package and co-located with readout electronics on thedistal tip of the device 10. It is appreciated that the infrared aspectof this disclosure may be used in conjunction with, or separate from,the other embodiments discussed herein. One such infrared system thatcould be used with the present disclosure is disclosed in U.S. Pat.

No. 6,652,452, the entirety of which is incorporated herein byreference.

The device 10 may also utilize Optical Coherence Tomography (hereinafter“OCT”) technology as a stand-alone detection system or in conjunctionwith the other embodiments disclosed herein. OCT is an optical signalacquisition and processing method that generates images using nearinfrared light. By way of background, OCT performs high-resolution,cross-sectional tomographic imaging of the internal microstructure inmaterials and biologic systems by measuring backscattered orback-reflected light. OCT images are typically two- or three-dimensionaldata sets that represent the optical back-scattering in across-sectional plane through the tissue. Image resolutions ofapproximately 1 to 15 micrometers may be achieved, one to two orders ofmagnitude higher than conventional ultrasound. Imaging can be performedin situ and in real time.

OCT forms depth resolved images by interferometrically detecting thelight backscattered from different scatterers within the sample. In atypical OCT system 50, as shown in FIG. 26, the light from the laser 52is split by a fiber optic coupler/beam splitter 54 into two arms i.e.the reference arm 56 and the sample arm 58. The light coupled into thereference arm 56 is reflected back from a fixed mirror 60, while in thesample arm 58 the light is projected through an OCT probe 62, which willbe discussed in greater detail below.

The OCT probe 62 may be focused onto the sample of interest (e.g. tissueor the anatomy of the patient) through a focusing lens (e.g. a GRINlens). OCT is a point by point imaging technique where the sample isilluminated by focusing the light from the laser 52 onto a small point(spot size determined by the focusing lens) on the sample. Light in thesample arm 58 travels within the tissue and is backscattered bydifferent scatterers within the tissue and combines with the light fromthe reference arm 56. If the optical path lengths of the reference 56and sample 58 arms are matched, an interferogram may be formed which maybe measured by a photo detector or a spectrometer. The frequency contentof the interferogram may contain information about the depth andstrength of the scatterers that the beam had encountered in the sample.The resulting interferogram may be processed to form one-dimensionaldepth information generally known as an A-scan (a single A-scan would bea single column in the image). The optical beam may then be scanned overthe sample to generate two- or three-dimensional images. The beam may bescanned using galvanometers in bench-top OCT systems or using MEMSscanners in hand-held OCT devices. This data is sent to, and processedby, the computer 95 or other processor.

As further disclosed in FIG. 27, the OCT probe 62 may include a GRINSlens 64, the diameter of which in this embodiment is 1 mm, but which canvary depending on the intended application. A single mode optical fiber66 is included in this embodiment that transfers the light rays betweenthe OCT

probe 62 and the remaining portion of the OCT system (e.g. the fiberoptic coupler 54 or a detector 68). The single mode optical fiber 66 mayhave a thickness of approximately 900 micrometers and a length ofapproximately 1.5 m. These specifications, of course, are examples onlyand can vary depending on the application. Attached to the distal end ofthe GRINS lens 64 may be a prism 70 for deflecting the light dependingon the location and orientation of the target. It can be appreciatedthat the prism 70 may not be necessary in situations where the surfaceof the target is directly in front of or substantially perpendicular tothe longitudinal axis of the light ray (or beam). In this embodiment,the length of the prism is approximately 700 micrometers, but it isappreciated that the length can vary and is application dependent

Two different embodiments of the OCT probe 62 are illustrated in FIG.28. The first embodiment is the forward image probe 72, which does notinclude a prism, such that the light ray (or beam) extends outwardtowards the front of the probe 72 to reach the target (e.g. tissue). Inthe second embodiment, image probe 74 contains a prism 70, which allowsthis embodiment to image targets that are disposed below or at an angleto the tip of the probe 74. The OCT technology may also be incorporatedin to the glove 110 in a manner as discussed above with respect to theultrasound embodiment.

Some of the parameters that may be manipulated to optimize OCT imaginginclude (a) the A-scan rate (the number of A-scans the system canacquire in a second), (b) the axial and transverse resolution, and (c)the imaging depth. The A-line scan rate may determine how fast an OCTsystem can operate. For a swept source OCT system, the imaging rate maydepend on the wavelength sweeping rate of the laser, while, for aspectral domain OCT system, it is generally limited by the speed of theline scan camera used in the spectrometer. The tradeoff is that at ahigher A-scan rate, the exposure time has to be reduced which candecrease the SNR of the acquired data. The axial resolution (resolutionacross the depth) is determined by the bandwidth and wavelength of thelaser source. In general, the higher the bandwidth the better is theaxial resolution. The resolution along the transverse dimensions isdetermined by the numerical aperture of the lens in the sample arm 58.The higher the numerical aperture, higher the transverse resolution,however, the tradeoff is a reduced depth-of-field. Moreover, with anincrease in the center wavelength of the source both the axial andtransverse resolutions degrade. Finally, the imaging depth is usuallylimited by how deeply the light can penetrate through the tissue orsample of interest. Higher wavelengths offer greater imaging depth.These and other parameters may be optimized to detect certain featuresof a patient's anatomy, such as nerve root.

The OCT probe 62 may be positioned at the distal portion 14 of thedevice 10. Alternatively, the OCT probe 62 may be positioned at thedistal end of a k-wire like structure and disposed through the conduit36. In either embodiment, the OCT probe 62 may be configured to image aportion of the patient's anatomy that is adjacent to (or in front of)the distal portion 14 of the device 10. The surgeon may insert the OCTprobe 62 to image the patient's anatomy as needed to reach the surgicalsite. The OCT system 50 may be configured to visually and/or audiblyindicate detection of select pre-selected portions of a patient'sanatomy (e.g. nerve root). As mentioned above, it can be appreciatedthat the OCT system can be used independently or in combination withother detection technologies described herein.

It is also contemplated that the device 10 can be used in conjunctionwith a neuromonitoring system to detect certain portions of a patient'sanatomy, including neural elements that include a nerve, nerve bundle,or nerve root. For the purposes of this discussion, the device 10 andneuromonitoring system will be discussed with respect to detecting apatient's spinal nerve but it is contemplated that the device 10 andneuromonitoring system may be used to detect other nerves (peripheraland central) as well as the spinal cord. One type of neuromonitoringsystem that may be used in conjunction with the device 10 is disclosedin U.S. Pat. No. 7,920,922, the entirety of which is incorporated byreference herein.

In one embodiment, stimulation electrodes may be placed at the distalend of the device 10, such as forming part of the tip 22, or placed at adistal end of an instrument, such as a K-wire, disposed through theconduit 36, to stimulate any nerves in the region adjacent to the distalportion 14 of the device 10. EMG (electromyography) electrodes can beplaced on the skin to detect any nerve depolarization in the mannerdescried in U.S. Pat. No. 7,920,922. One manner in which the proximity,location, direction, physiology of the nerve is determined is alsodisclosed in U.S. Pat. No. 7,920,922. It is appreciated that othertechniques of detecting nerves using stimulation are known in the artand any of those techniques may be used in conjunction, or integrated,with the device 10 in the manner described above.

The ultrasound imager 24 may be used in conjunction or independent of animage capture device to visualize the patient's anatomy as describedherein. Steps and methods describe herein using the ultrasound imager 24to detect certain features of a patient's anatomy may be supplementedthrough use of an image capture device. Specifically, the surgeon mayrely on the image or audio queues generated by the ultrasound imager 24to detect the presence (or absence) of a nerve thereby allowing thesurgery to reposition (or continue advancing) the device 10 through thepatient's anatomy towards the surgical site 48. The ultrasound imager 24may also be used to confirm the image captured by the image capturedevice is accurate by confirming the presence or absence of a targetedanatomical feature (e.g. nerve).

Likewise, in operation, the OCT system 50 may be used in conjunction orindependent of an image capture device and/or the ultrasound imager 24to scan and identify the patient's anatomy as described herein and toaccess the surgical site. Steps and methods used to access the surgicalsite and avoid target anatomy (e.g. nerve) employing the ultrasoundimager 24 may also be performed using the OCT system 50. Furthermore,steps described herein using ultrasound imager 24 may be supplementedthrough use of the OCT system 50. For example, the surgeon may rely onthe image or audio cues generated by the OCT system 50 to detect thepresence (or absence) of a nerve thereby allowing the surgery toreposition (or continue advancing) the device 10 through the patient'sanatomy towards the surgical site 48. The OCT system 50 may also be usedto confirm the image captured by an image capture device is accurate byconfirming the presence or absence of a targeted anatomical feature(e.g. nerve).

The device 10 may be used in a variety of other medical areas outside ofspinal surgery. These include: gynecologic transvaginal imaging forcervical cancer and endometrial cancer, prostate examination/prostatecancer, intra-abdominal surgery to delineate depth of penetration of atumor within peritoneal contents (stomach, small intestine, largeintestine, kidney, liver, and spleen). The device 10 may be utilizedwith known robotic systems, such as the Da Vinci Robotic or similarsystems.

FIG. 47 depicts an illustrative operating environment in which variousaspects of the present disclosure may be implemented in accordance withone or more example embodiments. Referring to FIG. 47, computing systemenvironment 4700 may be used according to one or more illustrativeembodiments. Computing system environment 4700 is only one example of asuitable computing environment and is not intended to suggest anylimitation as to the scope of use or functionality contained in thedisclosure. Computing system environment 4700 should not be interpretedas having any dependency or requirement relating to any one orcombination of components shown in illustrative computing systemenvironment 4700.

Computing system environment 4700 may include computing device 4701having processor 4703 for controlling overall operation of computingdevice 4701 and its associated components, including random-accessmemory (RAM) 4705, read-only memory (ROM) 4707, communications module4709, and memory 4715. Computing device 4701 may include a variety ofcomputer readable media. Computer readable media may be any availablemedia that may be accessed by computing device 4701, may benon-transitory, and may include volatile and nonvolatile, removable andnon-removable media implemented in any method or technology for storageof information such as computer-readable instructions, object code, datastructures, program modules, or other data. Examples of computerreadable media may include random access memory (RAM), read only memory(ROM), electronically erasable programmable read only memory (EEPROM),flash memory or other memory technology, compact disk read-only memory(CD-ROM), digital versatile disks (DVD) or other optical disk storage,magnetic cassettes, magnetic tape, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to storethe desired information and that can be accessed by computing device4701.

Although not required, various aspects described herein may be embodiedas a method, a data processing system, or as a computer-readable mediumstoring computer-executable instructions. For example, acomputer-readable medium storing instructions to cause a processor toperform steps of a method in accordance with aspects of the disclosedembodiments is contemplated. For example, aspects of the method stepsdisclosed herein may be executed on a processor on computing device4701. Such a processor may execute computer-executable instructionsstored on a computer-readable medium.

Software may be stored within memory 4715 and/or storage to provideinstructions to processor 4703 for enabling computing device 4701 toperform various functions. For example, memory 4715 may store softwareused by computing device 4701, such as operating system 4717,application programs 4719, and associated database 4721. Also, some orall of the computer executable instructions for computing device 4701may be embodied in hardware or firmware. Although not shown, RAM 4705may include one or more applications representing the application datastored in RAM 4705 while computing device 4701 is on and correspondingsoftware applications (e.g., software tasks) are running on computingdevice 4701.

Communications module 4709 may include a microphone, keypad, touchscreen, and/or stylus through which a user of computing device 4701 mayprovide input, and may also include one or more of a speaker forproviding audio output and a video display device for providing textual,audiovisual and/or graphical output. Computing system environment 4700may also include optical scanners (not shown). Illustrative usagesinclude scanning and converting paper documents, e.g., correspondence,receipts, and the like, to digital files.

Computing device 4701 may operate in a networked environment supportingconnections to one or more remote computing devices, such as computingdevices 4741, 4751, and 4761. Computing devices 4741, 4751, and 4761 maybe personal computing devices or servers that include any or all of theelements described above relative to computing device 4701. Computingdevice 4761 may be a mobile device (e.g., smart phone) communicatingover wireless carrier channel 4771.

The network connections depicted in FIG. 47 may include local areanetwork (LAN) 4725 and wide area network (WAN) 4729, as well as othernetworks. When used in a LAN networking environment, computing device4701 may be connected to LAN 4725 through a network interface or adapterin communications module 4709. When used in a WAN networkingenvironment, computing device 4701 may include a modem in communicationsmodule 4709 or other means for establishing communications over WAN4729, such as Internet 4731 or other type of computer network. Thenetwork connections shown are illustrative and other means ofestablishing a communications link between the computing devices may beused. Various well-known protocols such as transmission controlprotocol/Internet protocol (TCP/IP), Ethernet, file transfer protocol(FTP), hypertext transfer protocol (HTTP) and the like may be used, andthe system can be operated in a client-server configuration to permit auser to retrieve web pages from a web-based server. Any of variousconventional web browsers can be used to display and manipulate data onweb pages.

The disclosure is operational with numerous other general purpose orspecial purpose computing system environments or configurations.Examples of well-known computing systems, environments, and/orconfigurations that may be suitable for use with the disclosedembodiments include, but are not limited to, personal computers (PCs),server computers, hand-held or laptop devices, smart phones,multiprocessor systems, microprocessor-based systems, set top boxes,programmable consumer electronics, network PCs, minicomputers, mainframecomputers, distributed computing environments that include any of theabove systems or devices, and the like.

While aspects of the present disclosure have been described in terms ofpreferred examples, and it will be understood that the disclosure is notlimited thereto since modifications may be made to those skilled in theart, particularly in light of the foregoing teachings.

1. A device for scanning a part of an anatomy, the device comprising: ashaft having a distal end, a proximal end, and a longitudinal axis; ahousing disposed at the distal end; and at least one ultrasoundtransducer disposed in the housing, wherein the at least one ultrasoundtransducer is configured to scan a region distal to the housing, whereinthe shaft comprises a channel formed within the shaft, the channelextending from the distal end to the proximal end and configured toallow passage of a surgical tool through the shaft and housing via thechannel.
 2. The device of claim 1, wherein the channel has a diameter ina range of 24 mm to 40 mm.
 3. The device of claim 1, wherein the deviceis configured for continuous ultrasound imaging as the surgical tool ispassed through the channel.
 4. The device of claim 1, wherein thechannel is offset from the longitudinal axis of the shaft.
 5. The deviceof claim 1, wherein the channel is collinear with the longitudinal axisof the shaft.
 6. The device of claim 1, wherein the at least oneultrasound transducer comprises at least 100 ultrasound transducersevenly spaced within the housing.
 7. The device of claim 1, wherein theat least one ultrasound transducer is configured to emit an ultrasonicfrequency in a direction that is substantially parallel to thelongitudinal axis.
 8. The device of claim 1, wherein the at least oneultrasound transducer is configured to emit an ultrasonic frequency in adirection that is not parallel to the longitudinal axis.
 9. The deviceof claim 1, wherein the at least one ultrasound transducer comprises aplurality of ultrasound transducers arranged in more than one row on thedistal end of the shaft.
 10. The device of claim 1, wherein the at leastone ultrasound transducer may have a transducer frequency within a rangebetween 5 MHz to 20 MHz.